Large deformation extensometers, by the sensors, the adjusting lever with a hook, fixed rod, the landmark away from the stopper plate, and is provided for adjusting the rod portion and the sensor lower portion of a set of the symmetrical upper blade group, the lower blade group composition, wherein:provided in a lower portion of the fixed rod, and hooks mounted with the lower portion of the adjusting lever sensor for a drawout displacement sensor; the drawout sensor comprises a cartridge body, the rope, and the coil spring provided in the cassette body contraction mechanism A and encoder; saidvolumes reed contraction mechanism consolidation mainspring shaft, located in the shaft body from one end of the cartridge body can rotate around the axis of the spring plate and having one end fixed in the positioning axis other end fixed to the spring coil lumen disc-shaped hairconstituted; said one end of the wire rope is fixed in the spring on the disc leads to the wound by a winding sleeve and connected to the encoder shaft; the other end of the leads are directly connected to the hook; and by the hooks of the hook with the lower portion of the adjusting lever.articulated to form a large deformation the extensometers automatic telescopic mechanism.
The main technical parameters：

Model	E500B	E1200B
Stroke	500mm	1200mm
Gauge length（L0）	20-500mm	20-1000mm
Indication error (relative)	1%
Indication error	0.01mm%
Full-scale error	1%
Linearity error	0.05%
Gauge error（L0）	±1%
Resolution	0.005mm
Operating force	≤1N
Clamping force	25N（Adjustable）
Operating Temperature Range	0-50°C
Maximum thickness of the sample	10mm
The maximum width of the specimen	30mm
Maximum sample diameter	Ф10
Weight Approx.	26kg		31kg